This invention relates to a tilt mechanism for an outboard drive unit and more particularly to an improved hydraulic assembly for controlling the position of an outboard drive and an improved control valve arrangement therefore.
It is well known in marine outboard drives, be they either outboard motors or the outboard drive portion of an inboard/outboard drive, to mount the outboard drive for movement relative to the hull of the associated watercraft so that if an underwater obstacle is struck, the outboard drive may pop up to clear the watercraft obstacle without damage. Once the obstacle is cleared, the outboard drive is moveable back to its normal driving condition. The operation is controlled by a hydraulic unit which should also have sufficient resistant to movement so as to hold the outboard drive against popping up when operated in a reverse drive mode.
A wide variety of devices have been proposed for this purpose. However, it is well known to adjust the trim position of an outboard drive to suit various running conditions. For example, when operating in shallow water, the outboard drive may be trimmed up so as to not protrude too deeply into the water. However, when the trim is changed then the hydraulic unit cannot normally accommodate return to a variety of trim adjusted positions once an underwater obstacle is struck and cleared.
It has been proposed to employ a floating piston in the hydraulic unit which acts as a memory so that when an underwater obstacle is struck, the outboard drive may pop up and then return to the trim adjusted position as set by the position of the floating piston. These devices are quite effective. However, the use of the floating piston in the cylinder assembly increases its length and its complexity and thus has some disadvantages.
It is, therefore, a principal object to this invention to provide an improved hydraulic assembly for controlling the position of an outboard drive which will permit the outboard drive to pop up when an underwater obstacle is struck and will permit the outboard drive to return to any trim adjusted position once the underwater obstacle is cleared and without necessitating the use of a floating piston.
It is a further object to this invention to provide an improved and simplified hydraulic control circuitry for such a unit.
When a hydraulic control assembly of the type previously described is employed in conjunction with a marine outboard drive, although the operation of the outboard drive during normal operation can be as desired, the hydraulic unit gives considerable resistance to an operator tilting the outboard drive to a tilted up out-of-the water position. Therefore, it has been the normal practice to provide some form of bypass control valve that permits the shock absorbing valves of the hydraulic unit to be bypassed so that an operator can easily raise the outboard drive without fluid resistance. Normally these control valves are operated by a lever that is positioned on one side or the other of the outboard drive. However, with certain watercraft and certain applications, the control lever is not positioned on the side of the outboard drive that is the most accessible. Thus, certain difficulties occur.
It is, therefore, a still further object to this invention to provide an improved control valve assembly for permitting manual operation of the outboard drive and which is accessible from either side of the outboard drive.